Table saw insert with lock-down mechanism

ABSTRACT

Inserts for table saws are disclosed. The table inserts are equipped with a toolless locking mechanism that mechanically holds the insert in place and which allows for the installation and removal of the insert without the use of tools. The locking mechanism is easy to lock and unlock and yet robust enough to hold a zero-clearance insert in place.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of Ser. No. 12/931,809, filed Feb.11, 2011, which claims the benefit of and priority from U.S. ProvisionalPatent Application Ser. No. 61/338,493, filed Feb. 19, 2010. All of theabove listed patent applications are hereby incorporated by reference intheir entireties.

TECHNICAL FIELD

The present invention relates to inserts for table saws. The insertincludes a lock-down mechanism to hold the insert in place.

BACKGROUND

In a workshop environment, such as a wood-working workshop, a table sawis commonly used to cut a workpiece, such as a piece of wood, plastic,metal or the like. A table saw is a piece of power equipment that has aflat table to support a workpiece, and a blade extends up through anopening in the table. The workpiece is placed on the table and pushedforward into the spinning blade to make a cut.

In order to access the portion of the blade that is below the tablesurface for changing the blade or for other tasks, an opening is left inthe table, and during use, the opening is filled by a removable tableinsert. The insert has a flat surface to match the surface of the tableand a slot through which the blade extends. It is important that thetable insert be secured in the saw so that it does not come loose whilethe blade is spinning, as this would create a hazard.

Some inserts are designed as “zero-clearance” inserts. A zero-clearanceinsert has a slot that matches as closely as possible the profile orwidth of the blade. To achieve this, a zero-clearance insert ismanufactured without a slot for the blade. The zero-clearance insert isthen installed in a saw with the blade lowered to a position below thetable surface. The motor is turned on so that the blade spins and thespinning blade is slowly raised so that is cuts through thezero-clearance insert, leaving a slot in the insert that matches asclosely as possible the profile of the blade. It is particularlyimportant that the table insert be securely kept in place during thisprocess.

In the past, inserts have been held in place by screws that extendthrough a hole in the insert and thread into a bore in the table. Such aconfiguration, however, makes it inconvenient for a user to install orremove the insert because a screwdriver would be required. Also, thescrew could be lost or a screwdriver might not be readily available.

This document describes a table insert designed for a table saw whichmechanically, and easily, locks in place without the use of tools.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a table saw.

FIG. 2 shows a table insert with the lever of a locking mechanismpivoted down.

FIG. 3 shows a table insert with the lever of a locking mechanismpivoted up.

FIG. 4 shows a view of the table of the saw with some of the table andinsert removed.

FIG. 5 shows a cross-sectional view of FIG. 4.

FIG. 6 shows a view of the table of the saw with some of the tableremoved.

FIG. 7 shows a cross-sectional view of FIG. 6.

FIG. 8 shows the lever of a locking mechanism isolated.

FIG. 9 shows a side view of the locking mechanism lever of FIG. 8.

FIG. 10 shows a rear view of the locking mechanism lever of FIG. 8.

FIG. 11 shows a top view of the locking mechanism lever of FIG. 8.

FIG. 12 shows and alternative embodiment of a lever.

FIG. 13 shows a side view of the alternative lever of FIG. 12.

FIG. 14 shows a zero-clearance insert without a slot for a blade.

FIG. 15 shows a zero-clearance insert with a slot for a blade.

FIG. 16 shows, in cross-section, a lock-down mechanism using a T-shapedbolt.

FIG. 17 shows a cross-sectional view of the T-shaped bolt in use.

FIG. 18 shows the T-shaped bolt in a locked position.

FIG. 19 shows, in cross-section, a lock-down mechanism using a tab.

FIG. 20 shows a cross-sectional view of the tab of FIG. 19 in use.

FIG. 21 shows the tab of FIG. 19 isolated from other structure.

FIG. 22 shows a lock-down mechanism using a latch.

DETAILED DESCRIPTION

A table saw 10 is shown in FIG. 1. Saw 10 includes a table 12 and acircular blade 14. The blade extends up through a slot 16 in a tableinsert 18. The insert fits within an opening 20 in the table and the topsurface of the insert is nominally co-planar with the top surface of thetable. A piece of wood, or other material to be cut, is placed on thetable and pushed into contact with the spinning blade to make a cut. Ariving knife 22, or similar component such as a splitter, is mountedunder the table behind the blade and also extends up through a slot 24in table insert 18. Both the riving knife (or splitter) and the bladecan be moved up and down together by turning hand wheel 26, and can betilted from zero to forty-five degrees to the left by turning hand wheel28. Slots 16 and 24 in the table insert accommodate this movement.

As stated, table insert 18 covers opening 20 in table 12 of the saw.Opening 20 is an oblong opening with straight sides and semi-circles ateach end. Opening 20 surrounds the blade and riving knife and is largeenough to allow access to the internal saw assembly so that the operatorof the saw can change the blade, install or remove the riving knife, orperform other maintenance tasks. Table insert 18 is shaped to closelyfit within opening 20 and is designed to sit flush or nearly flush withthe table surface so that a workpiece may glide smoothly over the tableinsert without interference.

FIGS. 2 and 3 show table insert 18 isolated from the saw. The main body30 of the table insert 18 may be made of a rigid material that resistswarping, such as phenolic, or it may be made of plastic that isreinforced by an inner plate of steel or some other metal. Two frontleveling screws 32 and two rear leveling screws 34 are installed in thetable insert. The ends of the leveling screws adjacent the top of theinsert have a molded hexagonal inset in which the end of a hex wrenchcan be inserted to turn the screw. The opposite or lower ends of thefront and rear leveling screws contact ledges 36 and 38, respectively,that extend underneath the table insert from the underside of table 12,as shown in FIGS. 5 and 7. The screws allow the operator of the saw toadjust the height of the table insert so that the surface of the tableinsert is flush, or nearly flush, with the surface of table 12. Twopositioning set screws 40, one along the middle of the right side of thetable insert and one towards the middle of the rear side of the tableinsert, allow the table insert to be adjusted so that it fits snugglyside-to-side within opening 20. Two generally rectangular metal plates42, one along either side of opening 24 in the table insert, providehard contact surfaces for the sharp tips of anti-kickback pawls that aretypically mounted to a splitter incorporated in a blade guard. A smallcutout 44 in the left plate helps prevent an anti-kickback pawl fromcatching on the rear leveling screw.

The rear of insert 18 is held securely in place by the rear levelingscrews 34. The bottom end of each rear leveling screw includes a headthat overlaps the heads of screws threaded into tabs 38 on table 12, asshown in FIG. 7. The overlap locks down the rear of the insert andprevents the rear of the insert from rising up. As the table insert isinstalled or removed, the front end is held higher than the back end sothat the table insert is at a slight angle. This allows the heads of therear leveling screws to slide under, or out from under, the heads ofscrews that are mounted in the table on ledges 38.

The front of table insert 18 is held securely in place within opening 20by a mechanical locking mechanism that consists of a lever 46 that worksin conjunction with ledges 36 formed on the underside of table 12. Asshown in FIGS. 2 and 3, lever 46 has a handle 48 made of a narrow stripof metal bent to form a semi-circular shape that matches the front endof insert 18. In order for the table insert to fit within opening 20,some material from the main body 30 of the table insert is removed atthe front end so there is room for lever 46 to fit along the outside ofthe main body.

FIGS. 8-11 show various views of lever 46 isolated. There is a hole 52,shown in FIG. 8, at each end of handle 48, and a screw 54 passes througheach hole to attach each end of lever 46 to the right and left side ofthe insert 18 in such a way to allow the lever to pivot upward aboutthose screws, as shown in FIG. 3. A lift tab 56 is formed at the frontof lever 46 by a small, semicircular shaped extension along the top edgeof the lever, at the middle of the lever. The extension or tab is bentinward so that it is at a right angle to the front side of the lever.Table insert 18 has a recessed area 58 below lift tab 56 that is shapedso that tab 56 is substantially flush with the table top when the leveris down as shown in FIG. 2. The recessed area is also large enough toallow the operator of the saw to place a finger underneath the lift tabin order to lift lever 46 and pivot it upward.

Near each end of lever 46, just before holes 52, a side portion 50extends down below the table insert, as shown in FIG. 2. At the bottomof each side portion, a projection bends inward at a right angle tocreate a tab 60, as shown in FIGS. 8 and 11. The front edge 62 of eachtab 60 is shaped to contact the underside of table insert 18 when lever46 pivots upward to limit how far the lever can pivot upward, as shownin FIG. 3.

The rear of each tab 60 extends out to form arms 64. Each arm 64 slopesupward for a length and then curves back down slightly at the end toterminate in contact areas 66, as shown in FIG. 8. Arms 64 are shapedand sized to fit under ledges 36 in the table when lever 46 is pivoteddown to hold the insert in place.

As shown in the cross-sectional view of FIG. 5, arms 64 are positionedjust below ledges 36 on either side of the table insert when the tableinsert is fully installed. There may be a small gap between the top ofarm 64 and the underside of the ledge. In the case of an upward force onthe table insert, contact areas 66 at the top of the curved ends of eacharm 64 will contact the underside of ledges 36.

Contact areas 66 are positioned directly below the pivot axis of lever46 (which runs through the center of each screw 54), or forward of thepivot axis (forward meaning toward lift tab 56) so that an upward forceacting on the table insert will not tend to pivot lever 46 up; rather,lever 46 will remain locked in place. In the depicted embodiment thecontact areas are directly below the pivot axes. If the contact areaswere past the pivot axes toward the rear of the insert, an upward forceon the table insert would tend to pivot lever 46 up and the table insertcould be dislodged.

Arms 64 are strong enough to resist an upward force on the table insert,but also flexible enough to be bent with a tool in order to fit underthicker or thinner ledges 36, as the thickness of the ledges may varybetween different saw tables. An alternative configuration of arms 64are shown in FIGS. 12 and 13. In this configuration, arms 64 are notconfigured to be bent to accommodate ledges 36 of varying thickness.

FIG. 14 shows a zero-clearance insert with a lock-down lever before theslot is cut for the blade. To cut a slot for the blade, a user wouldlower the blade and position the insert in the table opening and makesure the insert was locked down by the rear screws and the frontlock-down lever. The user may also place a board across the top of theinsert and clamp the board to the saw table. The user would then startthe saw and slowly raise the blade. The spinning blade would cut a slotin the insert as the blade rises, and the lock-down lever and rearscrews would help hold the insert in place against the upward force ofthe rising blade. A zero-clearance insert with a blade slot is shown inFIG. 15.

Lever 46 also acts as a handle when pivoted up, which can be used tofacilitate installation or removal of the insert from the saw. To removethe insert, a user would place a finger under lift tab 56, pivot lever46 up to move arms 64 out from under ledges 36, hold and lift up thelever slightly to cause the front end of the insert to rise, and thenslide the insert towards the front of the saw to disengage theoverlapping rear screws and remove the insert from the saw. The processis repeated in reverse to install the insert in the saw.

FIGS. 16-18 show another embodiment of a lock-down mechanism for a tablesaw insert. The mechanism includes a T-shaped bolt 70 that threads intoa threaded hole 72 in a ledge 74 that extends under the front of theinsert from the underside of table 12. A large circular recess 76 in thetop of the insert surrounds a slot 78 at the front of the table insertabove hole 72. The bar 80 along the top of the T-lock, which forms thehorizontal portion of the “T”, sits within the circular cutout. Thecircular cutout is large enough that the operator of the saw may rotatethe bar 80. When bar 80 is rotated so that it is at a 90 degree anglewith slot 78, the table insert will be locked in place. When bar 80 isrotated so that it is parallel with slot 78, the table insert may beremoved by placing a finger through another hole 82 in the insert andlifting the front end up allowing bar 80 to pass through slot 78.

FIGS. 19-21 show another lock-down mechanism to secure an insert inplace. In this embodiment, a metal tab 90 is attached to the table underthe insert and extends up through an opening 92 in the insert. In FIG.20 the tab is attached to the table by screw 94. Normally, the tab is ina closed position with the shoulders or edges 96 of the wider topportion of the tab resting upon a sunken surface 98 on the insert. Torelease the insert, a user flexes the tab so that the upper portion ofthe tab is moved off of surface 98 into opening 92 where it clears thetable insert. With the tab flexed, a user reaches through opening 82 inthe insert to lift and remove the insert.

FIG. 22 shows another lock-down mechanism to secure an insert in place.In this embodiment, a latch 100 pivots under the insert to hold theinsert in place. The latch 100 may be designed to lock the insert inplace in many different ways. For example, the latch may pivot so thatone end of the latch is under table 12 or it may pivot so that a notchin one end of the latch fits under the head of a screw 102 that isthreaded into the table. In any case, latch 100 pivots around screw 104and a spring 106 biases the latch closed. To open the latch and removethe insert, a user reaches through opening 82 in the insert, pivots thelatch and lifts up the insert.

The lock-down structures described herein may be thought of asmechanical lock-down means for holding the insert in place. Theselock-down structures hold an insert in place, and prevent the insertfrom moving up, through a physical abutment of parts or through what maybe thought of as an inelastic interaction of parts, while still allowinga user to release the lock-down structure and remove the insert withoutthe use of a screwdriver, wrench or other tool. For example, arms on alever may abut or interact with a ledge, and the lever may be pivoted byhand to release the interaction. The top of a T-shaped bolt may abut orinteract with a surface on the insert, and the T-shaped bolt can beturned by hand to release the abutment. An edge or shoulder on a tab mayabut or interact with a surface on an insert, and the tab can be flexedto release the abutment. A latch may abut or interact with a screw orsome other surface, and a user can pivot the latch to release theinteraction. These types of interactions may be referred to as positivemechanical interactions or as hand-operable mechanical locks. Thesestructures would have to undergo an inelastic deformation for the insertto be removed other than by releasing the lock-down structure. This isin contrast to prior mechanisms used to keep an insert in place, such asspring-biased buttons, spring-biased rollers, or leaf springs designedto flex into and out of a notch. These types of mechanisms do not holdthe insert in place against an upward force, such as a user pulling upon the insert to remove the insert, or such as cutting a slot in azero-clearance insert, and therefore do not mechanically lock the insertdown.

INDUSTRIAL APPLICABILITY

The table inserts with toolless lock-down mechanisms disclosed hereinare applicable to woodworking power tool equipment, and particularly totable saws. The described inserts provide a simple and effective meansfor securing and removing an insert without the use of tools.

It is believed that the disclosure set forth above encompasses multipledistinct inventions with independent utility. While each of theseinventions has been disclosed in its preferred form, the specificembodiments thereof as disclosed and illustrated herein are not to beconsidered in a limiting sense as numerous variations are possible. Thesubject matter of the inventions includes all novel and non-obviouscombinations and sub-combinations of the various elements, features,functions and/or properties disclosed herein. No single feature,function, element or property of the disclosed embodiments is essentialto all of the disclosed inventions. Similarly, where the claims recite“a” or “a first” element of the equivalent thereof, such claims shouldbe understood to include incorporation of one or more such elements,neither requiring nor excluding two or more such elements.

It is believed that the following claims particularly point out certaincombinations and sub-combinations that are directed to one of thedisclosed inventions and are novel and non-obvious. Inventions embodiedin other combinations and sub-combinations of features, functions,elements and/or properties may be claimed through amendment of thepresent claims or presentation of new claims in this or a relatedapplication. Such amended or new claims, whether they are directed to adifferent invention or directed to the same invention, whetherdifferent, broader, narrower or equal in scope to the original claims,are also regarded as included within the subject matter of theinventions of the present disclosure.

1. A table saw comprising: a table; a blade configured to extend atleast partially above the table when cutting; and an insert with amechanical lock-down; where the insert is configured to be installed andremoved by hand without tools; and where the mechanical lock-down isconfigured so that when the insert is installed in the saw themechanical lock-down can be moved by hand without tools between anengaged condition and a non-engaged condition; where the mechanicallock-down prevents the insert from being removed by an inelasticinteraction of parts when in the engaged condition; and where themechanical lock-down does not prevent the insert from being removed whenin the non-engaged condition.
 2. The table saw of claim 1, where thetable includes a ledge, and where the inelastic interaction of partsincludes an arm configured to abut the ledge.
 3. The table saw of claim1, where the inelastic interaction of parts includes a finger-rotatablebolt.
 4. The table saw of claim 3, where the finger-rotatable bolt is aT-shaped bolt.
 5. The table saw of claim 1, where the inelasticinteraction of parts includes a tab with edges that abut a surface onthe insert.
 6. The table saw of claim 1, where the inelastic interactionof parts includes a pivotable latch.